Get rid of base::SharedMemory::NULLHandle();

This CL is a refactor and has no intended behavior change.

NullHandle() has two use cases:
  * Create an invalid handle.
  * Return an object that can be compared against a handle to check validity.
The former is also the behavior of the default constructor of
base::SharedMemoryHandle, and the latter should be done with the member
IsValid().

Fixing the latter also allows the removal of operator== and operator!=.

BUG=713763
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2849633002
Cr-Commit-Position: refs/heads/master@{#468231}

base/memory/shared_memory.h

@@ -92,17 +92,15 @@ class BASE_EXPORT SharedMemory {
   // invalid value; NULL for a HANDLE and -1 for a file descriptor)
   static bool IsHandleValid(const SharedMemoryHandle& handle);
 
-  // Returns invalid handle (see comment above for exact definition).
-  static SharedMemoryHandle NULLHandle();
-
   // Closes a shared memory handle.
   static void CloseHandle(const SharedMemoryHandle& handle);
 
   // Returns the maximum number of handles that can be open at once per process.
   static size_t GetHandleLimit();
 
-  // Duplicates The underlying OS primitive. Returns NULLHandle() on failure.
-  // The caller is responsible for destroying the duplicated OS primitive.
+  // Duplicates The underlying OS primitive. Returns an invalid handle on
+  // failure. The caller is responsible for destroying the duplicated OS
+  // primitive.
   static SharedMemoryHandle DuplicateHandle(const SharedMemoryHandle& handle);
 
 #if defined(OS_POSIX)

base/memory/shared_memory_handle.h

@@ -83,10 +83,6 @@ class BASE_EXPORT SharedMemoryHandle {
                      mach_vm_size_t size,
                      base::ProcessId pid);
 
-  // Comparison operators.
-  bool operator==(const SharedMemoryHandle& handle) const;
-  bool operator!=(const SharedMemoryHandle& handle) const;
-
   // Duplicates the underlying OS resources.
   SharedMemoryHandle Duplicate() const;
 
@@ -106,10 +102,6 @@ class BASE_EXPORT SharedMemoryHandle {
 #elif defined(OS_WIN)
   SharedMemoryHandle(HANDLE h, base::ProcessId pid);
 
-  // Comparison operators.
-  bool operator==(const SharedMemoryHandle& handle) const;
-  bool operator!=(const SharedMemoryHandle& handle) const;
-
   // Whether |pid_| is the same as the current process's id.
   bool BelongsToCurrentProcess() const;
 

base/memory/shared_memory_handle_mac.cc

@@ -91,26 +91,6 @@ SharedMemoryHandle SharedMemoryHandle::Duplicate() const {
   }
 }
 
-bool SharedMemoryHandle::operator==(const SharedMemoryHandle& handle) const {
-  if (!IsValid() && !handle.IsValid())
-    return true;
-
-  if (type_ != handle.type_)
-    return false;
-
-  switch (type_) {
-    case POSIX:
-      return file_descriptor_.fd == handle.file_descriptor_.fd;
-    case MACH:
-      return memory_object_ == handle.memory_object_ && size_ == handle.size_ &&
-             pid_ == handle.pid_;
-  }
-}
-
-bool SharedMemoryHandle::operator!=(const SharedMemoryHandle& handle) const {
-  return !(*this == handle);
-}
-
 bool SharedMemoryHandle::IsValid() const {
   switch (type_) {
     case POSIX:

base/memory/shared_memory_handle_win.cc

@@ -30,18 +30,6 @@ SharedMemoryHandle& SharedMemoryHandle::operator=(
   return *this;
 }
 
-bool SharedMemoryHandle::operator==(const SharedMemoryHandle& handle) const {
-  // Invalid handles are always equal.
-  if (!IsValid() && !handle.IsValid())
-    return true;
-
-  return handle_ == handle.handle_ && pid_ == handle.pid_;
-}
-
-bool SharedMemoryHandle::operator!=(const SharedMemoryHandle& handle) const {
-  return !(*this == handle);
-}
-
 void SharedMemoryHandle::Close() const {
   DCHECK(handle_ != nullptr);
   DCHECK(BelongsToCurrentProcess());

base/memory/shared_memory_mac.cc

@@ -108,11 +108,6 @@ bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle.IsValid();
 }
 
-// static
-SharedMemoryHandle SharedMemory::NULLHandle() {
-  return SharedMemoryHandle();
-}
-
 // static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   handle.Close();

base/memory/shared_memory_nacl.cc

@@ -37,11 +37,6 @@ bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle.IsValid();
 }
 
-// static
-SharedMemoryHandle SharedMemory::NULLHandle() {
-  return SharedMemoryHandle();
-}
-
 // static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   DCHECK(handle.IsValid());

base/memory/shared_memory_posix.cc

@@ -57,11 +57,6 @@ bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle.IsValid();
 }
 
-// static
-SharedMemoryHandle SharedMemory::NULLHandle() {
-  return SharedMemoryHandle();
-}
-
 // static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   DCHECK(handle.IsValid());

base/memory/shared_memory_win.cc

@@ -170,11 +170,6 @@ bool SharedMemory::IsHandleValid(const SharedMemoryHandle& handle) {
   return handle.IsValid();
 }
 
-// static
-SharedMemoryHandle SharedMemory::NULLHandle() {
-  return SharedMemoryHandle();
-}
-
 // static
 void SharedMemory::CloseHandle(const SharedMemoryHandle& handle) {
   handle.Close();

components/discardable_memory/service/discardable_shared_memory_manager.cc

@@ -440,7 +440,7 @@ void DiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemory(
   MemorySegmentMap& client_segments = clients_[client_id];
   if (client_segments.find(id) != client_segments.end()) {
     LOG(ERROR) << "Invalid discardable shared memory ID";
-    *shared_memory_handle = base::SharedMemory::NULLHandle();
+    *shared_memory_handle = base::SharedMemoryHandle();
     return;
   }
 
@@ -461,14 +461,14 @@ void DiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemory(
   std::unique_ptr<base::DiscardableSharedMemory> memory(
       new base::DiscardableSharedMemory);
   if (!memory->CreateAndMap(size)) {
-    *shared_memory_handle = base::SharedMemory::NULLHandle();
+    *shared_memory_handle = base::SharedMemoryHandle();
     return;
   }
 
   base::CheckedNumeric<size_t> checked_bytes_allocated = bytes_allocated_;
   checked_bytes_allocated += memory->mapped_size();
   if (!checked_bytes_allocated.IsValid()) {
-    *shared_memory_handle = base::SharedMemory::NULLHandle();
+    *shared_memory_handle = base::SharedMemoryHandle();
     return;
   }
 

components/nacl/common/nacl_types.cc

@@ -16,8 +16,7 @@ NaClStartParams::NaClStartParams()
 #endif
       validation_cache_enabled(false),
       enable_debug_stub(false),
-      process_type(kUnknownNaClProcessType),
-      crash_info_shmem_handle(base::SharedMemory::NULLHandle()) {
+      process_type(kUnknownNaClProcessType) {
 }
 
 NaClStartParams::NaClStartParams(const NaClStartParams& other) = default;
@@ -91,9 +90,7 @@ NaClLaunchResult::NaClLaunchResult()
     : ppapi_ipc_channel_handle(),
       trusted_ipc_channel_handle(),
       plugin_pid(base::kNullProcessId),
-      plugin_child_id(0),
-      crash_info_shmem_handle(base::SharedMemory::NULLHandle()) {
-}
+      plugin_child_id(0) {}
 
 NaClLaunchResult::NaClLaunchResult(
     const IPC::ChannelHandle& ppapi_ipc_channel_handle,

components/nacl/renderer/nexe_load_manager.cc

@@ -81,8 +81,7 @@ std::string LookupAttribute(const std::map<std::string, std::string>& args,
 
 }  // namespace
 
-NexeLoadManager::NexeLoadManager(
-    PP_Instance pp_instance)
+NexeLoadManager::NexeLoadManager(PP_Instance pp_instance)
     : pp_instance_(pp_instance),
       nacl_ready_state_(PP_NACL_READY_STATE_UNSENT),
       nexe_error_reported_(false),
@@ -91,7 +90,6 @@ NexeLoadManager::NexeLoadManager(
       nexe_size_(0),
       plugin_instance_(content::PepperPluginInstance::Get(pp_instance)),
       nonsfi_(false),
-      crash_info_shmem_handle_(base::SharedMemory::NULLHandle()),
       weak_factory_(this) {
   set_exit_status(-1);
   SetLastError("");

content/browser/media/capture/web_contents_video_capture_device_unittest.cc

@@ -300,7 +300,7 @@ class StubClient : public media::VideoCaptureDevice::Client {
         VideoFrame::WrapExternalSharedMemory(
             media::PIXEL_FORMAT_I420, format.frame_size, visible_rect,
             format.frame_size, buffer_access->data(),
-            buffer_access->mapped_size(), base::SharedMemory::NULLHandle(), 0u,
+            buffer_access->mapped_size(), base::SharedMemoryHandle(), 0u,
             base::TimeDelta());
     const gfx::Point center = visible_rect.CenterPoint();
     const int center_offset_y =

content/browser/renderer_host/clipboard_message_filter_unittest.cc

@@ -123,7 +123,7 @@ TEST_F(ClipboardMessageFilterTest, ImageSizeOverflows32BitRowBytes) {
 }
 
 TEST_F(ClipboardMessageFilterTest, InvalidSharedMemoryHandle) {
-  CallWriteImageDirectly(gfx::Size(5, 5), base::SharedMemory::NULLHandle());
+  CallWriteImageDirectly(gfx::Size(5, 5), base::SharedMemoryHandle());
   uint64_t sequence_number =
       clipboard()->GetSequenceNumber(ui::CLIPBOARD_TYPE_COPY_PASTE);
   CallCommitWrite();

content/browser/renderer_host/render_message_filter.cc

@@ -239,7 +239,6 @@ void RenderMessageFilter::SendLoadFontReply(IPC::Message* reply,
   if (result->font_data_size == 0 || result->font_id == 0) {
     result->font_data_size = 0;
     result->font_id = 0;
-    handle = base::SharedMemory::NULLHandle();
   } else {
     result->font_data.GiveToProcess(base::GetCurrentProcessHandle(), &handle);
   }

content/browser/renderer_host/render_widget_host_view_aura_unittest.cc

@@ -2869,8 +2869,8 @@ TEST_F(RenderWidgetHostViewAuraTest, DiscardDelegatedFrames) {
       display_compositor::HostSharedBitmapManager::current());
 
   for (size_t i = 0; i < (renderer_count - 1) * handles_per_frame; i++) {
-    bitmap_client.ChildAllocatedSharedBitmap(
-        1, base::SharedMemory::NULLHandle(), cc::SharedBitmap::GenerateId());
+    bitmap_client.ChildAllocatedSharedBitmap(1, base::SharedMemoryHandle(),
+                                             cc::SharedBitmap::GenerateId());
   }
 
   // Hiding this last bitmap should evict all but two frames.

content/renderer/media/audio_message_filter_unittest.cc

@@ -54,7 +54,7 @@ class MockAudioDelegate : public media::AudioOutputIPCDelegate {
     device_status_ = media::OUTPUT_DEVICE_STATUS_ERROR_INTERNAL;
 
     created_received_ = false;
-    handle_ = base::SharedMemory::NULLHandle();
+    handle_ = base::SharedMemoryHandle();
     length_ = 0;
 
     volume_received_ = false;
@@ -130,7 +130,7 @@ TEST(AudioMessageFilterTest, Basic) {
   const uint32_t kLength = 1024;
   EXPECT_FALSE(delegate.created_received());
   filter->OnMessageReceived(AudioMsg_NotifyStreamCreated(
-      kStreamId, base::SharedMemory::NULLHandle(), socket_descriptor, kLength));
+      kStreamId, base::SharedMemoryHandle(), socket_descriptor, kLength));
   EXPECT_TRUE(delegate.created_received());
   EXPECT_FALSE(base::SharedMemory::IsHandleValid(delegate.handle()));
   EXPECT_EQ(kLength, delegate.length());

content/renderer/pepper/mock_renderer_ppapi_host.cc

@@ -87,7 +87,7 @@ base::SharedMemoryHandle
 MockRendererPpapiHost::ShareSharedMemoryHandleWithRemote(
     const base::SharedMemoryHandle& handle) {
   NOTIMPLEMENTED();
-  return base::SharedMemory::NULLHandle();
+  return base::SharedMemoryHandle();
 }
 
 bool MockRendererPpapiHost::IsRunningInProcess() const { return false; }

content/renderer/pepper/pepper_audio_input_host.cc

@@ -67,9 +67,7 @@ void PepperAudioInputHost::StreamCreated(
 }
 
 void PepperAudioInputHost::StreamCreationFailed() {
-  OnOpenComplete(PP_ERROR_FAILED,
-                 base::SharedMemory::NULLHandle(),
-                 0,
+  OnOpenComplete(PP_ERROR_FAILED, base::SharedMemoryHandle(), 0,
                  base::SyncSocket::kInvalidHandle);
 }
 
@@ -144,7 +142,7 @@ void PepperAudioInputHost::OnOpenComplete(
   if (result == PP_OK) {
     IPC::PlatformFileForTransit temp_socket =
         IPC::InvalidPlatformFileForTransit();
-    base::SharedMemoryHandle temp_shmem = base::SharedMemory::NULLHandle();
+    base::SharedMemoryHandle temp_shmem;
     result = GetRemoteHandles(
         scoped_socket, scoped_shared_memory, &temp_socket, &temp_shmem);
 

content/renderer/pepper/pepper_audio_output_host.cc

@@ -86,7 +86,7 @@ void PepperAudioOutputHost::StreamCreated(
 }
 
 void PepperAudioOutputHost::StreamCreationFailed() {
-  OnOpenComplete(PP_ERROR_FAILED, base::SharedMemory::NULLHandle(), 0,
+  OnOpenComplete(PP_ERROR_FAILED, base::SharedMemoryHandle(), 0,
                  base::SyncSocket::kInvalidHandle);
 }
 
@@ -182,7 +182,7 @@ void PepperAudioOutputHost::OnOpenComplete(
   if (result == PP_OK) {
     IPC::PlatformFileForTransit temp_socket =
         IPC::InvalidPlatformFileForTransit();
-    base::SharedMemoryHandle temp_shmem = base::SharedMemory::NULLHandle();
+    base::SharedMemoryHandle temp_shmem;
     result = GetRemoteHandles(scoped_socket, scoped_shared_memory, &temp_socket,
                               &temp_shmem);
 

content/renderer/renderer_blink_platform_impl.cc

@@ -546,8 +546,7 @@ bool RendererBlinkPlatformImpl::SandboxSupport::LoadFont(NSFont* src_font,
     return false;
   }
 
-  if (font_data_size == 0 || font_data == base::SharedMemory::NULLHandle() ||
-      *font_id == 0) {
+  if (font_data_size == 0 || !font_data.IsValid() || *font_id == 0) {
     LOG(ERROR) << "Bad response from RenderProcessHostMsg_LoadFont() for " <<
         src_font_descriptor.font_name;
     *out = NULL;

gpu/ipc/client/gpu_channel_host.cc

@@ -227,7 +227,7 @@ void GpuChannelHost::RemoveRoute(int route_id) {
 base::SharedMemoryHandle GpuChannelHost::ShareToGpuProcess(
     const base::SharedMemoryHandle& source_handle) {
   if (IsLost())
-    return base::SharedMemory::NULLHandle();
+    return base::SharedMemoryHandle();
 
   return base::SharedMemory::DuplicateHandle(source_handle);
 }

media/base/video_frame.cc

@@ -231,7 +231,7 @@ scoped_refptr<VideoFrame> VideoFrame::WrapExternalData(
     base::TimeDelta timestamp) {
   return WrapExternalStorage(format, STORAGE_UNOWNED_MEMORY, coded_size,
                              visible_rect, natural_size, data, data_size,
-                             timestamp, base::SharedMemory::NULLHandle(), 0);
+                             timestamp, base::SharedMemoryHandle(), 0);
 }
 
 // static
@@ -925,7 +925,6 @@ VideoFrame::VideoFrame(VideoPixelFormat format,
       coded_size_(coded_size),
       visible_rect_(visible_rect),
       natural_size_(natural_size),
-      shared_memory_handle_(base::SharedMemory::NULLHandle()),
       shared_memory_offset_(0),
       timestamp_(timestamp),
       unique_id_(g_unique_id_generator.GetNext()) {

media/capture/content/thread_safe_capture_oracle.cc

@@ -141,7 +141,7 @@ bool ThreadSafeCaptureOracle::ObserveEventAndDecideCapture(
   *storage = VideoFrame::WrapExternalSharedMemory(
       params_.requested_format.pixel_format, coded_size,
       gfx::Rect(visible_size), visible_size, output_buffer_access->data(),
-      output_buffer_access->mapped_size(), base::SharedMemory::NULLHandle(), 0u,
+      output_buffer_access->mapped_size(), base::SharedMemoryHandle(), 0u,
       base::TimeDelta());
   // If creating the VideoFrame wrapper failed, call DidCaptureFrame() with
   // !success to execute the required post-capture steps (tracing, notification

mojo/edk/embedder/embedder.h

@@ -109,8 +109,8 @@ CreateSharedBufferWrapper(base::SharedMemoryHandle shared_memory_handle,
 // |MojoHandle| and closes the handle. If successful, |num_bytes| will contain
 // the size of the shared memory buffer and |read_only| will contain whether the
 // buffer handle is read-only. Both |num_bytes| and |read_only| may be null.
-// Note: The value of |shared_memory_handle| may be
-// base::SharedMemory::NULLHandle(), even if this function returns success.
+// Note: |shared_memory_handle| may be invalid even if this function returns
+// success.
 // Callers should perform appropriate checks.
 MOJO_SYSTEM_IMPL_EXPORT MojoResult
 PassSharedMemoryHandle(MojoHandle mojo_handle,

ppapi/nacl_irt/ppapi_dispatcher.cc

@@ -74,7 +74,7 @@ IPC::PlatformFileForTransit PpapiDispatcher::ShareHandleWithRemote(
 base::SharedMemoryHandle PpapiDispatcher::ShareSharedMemoryHandleWithRemote(
     const base::SharedMemoryHandle& handle,
     base::ProcessId remote_pid) {
-  return base::SharedMemory::NULLHandle();
+  return base::SharedMemoryHandle();
 }
 
 std::set<PP_Instance>* PpapiDispatcher::GetGloballySeenInstanceIDSet() {

ppapi/proxy/gamepad_resource.cc

@@ -103,7 +103,7 @@ void GamepadResource::Sample(PP_Instance /* instance */,
 void GamepadResource::OnPluginMsgSendMemory(
     const ResourceMessageReplyParams& params) {
   // On failure, the handle will be null and the CHECK below will be tripped.
-  base::SharedMemoryHandle handle = base::SharedMemory::NULLHandle();
+  base::SharedMemoryHandle handle;
   params.TakeSharedMemoryHandleAtIndex(0, &handle);
 
   shared_memory_.reset(new base::SharedMemory(handle, true));

ppapi/proxy/media_stream_track_resource_base.cc

@@ -70,7 +70,7 @@ void MediaStreamTrackResourceBase::OnPluginMsgInitBuffers(
     int32_t number_of_buffers,
     int32_t buffer_size,
     bool readonly) {
-  base::SharedMemoryHandle shm_handle = base::SharedMemory::NULLHandle();
+  base::SharedMemoryHandle shm_handle;
   params.TakeSharedMemoryHandleAtIndex(0, &shm_handle);
   buffer_manager_.SetBuffers(number_of_buffers, buffer_size,
                              std::unique_ptr<base::SharedMemory>(