Use container::back() and container::pop_back() in components/

Also convert !container.size() to container.empty().

Review-Url: https://codereview.chromium.org/2117233002
Cr-Commit-Position: refs/heads/master@{#404289}

components/autofill/content/renderer/autofill_agent.cc

@@ -120,10 +120,8 @@ void GetDataListSuggestions(const WebInputElement& element,
     std::vector<base::string16> parts = base::SplitString(
         prefix, base::ASCIIToUTF16(","), base::TRIM_WHITESPACE,
         base::SPLIT_WANT_ALL);
-    if (!parts.empty()) {
-      base::TrimWhitespace(parts[parts.size() - 1], base::TRIM_LEADING,
-                           &prefix);
-    }
+    if (!parts.empty())
+      base::TrimWhitespace(parts.back(), base::TRIM_LEADING, &prefix);
   }
 
   // Prefix filtering.
@@ -500,7 +498,7 @@ void AutofillAgent::AcceptDataListSuggestion(
       }
     }
     last_part.append(suggested_value);
-    parts[parts.size() - 1] = last_part;
+    parts.back() = last_part;
 
     new_value = base::JoinString(parts, base::ASCIIToUTF16(","));
   }

components/autofill/core/browser/form_structure.cc

@@ -448,10 +448,7 @@ bool FormStructure::EncodeQueryRequest(
     encoded_signatures->push_back(signature);
   }
 
-  if (!encoded_signatures->size())
-    return false;
-
-  return true;
+  return !encoded_signatures->empty();
 }
 
 // static

components/data_reduction_proxy/core/common/data_reduction_proxy_headers.cc

@@ -59,7 +59,7 @@ bool StartsWithActionPrefix(base::StringPiece header_value,
                             base::StringPiece action_prefix) {
   DCHECK(!action_prefix.empty());
   // A valid action does not include a trailing '='.
-  DCHECK(action_prefix[action_prefix.size() - 1] != kActionValueDelimiter);
+  DCHECK(action_prefix.back() != kActionValueDelimiter);
 
   return header_value.size() > action_prefix.size() + 1 &&
          header_value[action_prefix.size()] == kActionValueDelimiter &&

components/display_compositor/gl_helper_unittest.cc

@@ -258,10 +258,8 @@ class GLHelperTest : public testing::Test {
     }
 
     // Check the output size matches the destination of the last stage
-    EXPECT_EQ(scaler_stages[scaler_stages.size() - 1].dst_size.width(),
-              dst_size.width());
-    EXPECT_EQ(scaler_stages[scaler_stages.size() - 1].dst_size.height(),
-              dst_size.height());
+    EXPECT_EQ(scaler_stages.back().dst_size.width(), dst_size.width());
+    EXPECT_EQ(scaler_stages.back().dst_size.height(), dst_size.height());
 
     // Used to verify that up-scales are not attempted after some
     // other scale.

components/gcm_driver/crypto/gcm_encryption_provider.cc

@@ -31,7 +31,7 @@ const base::FilePath::CharType kEncryptionDirectoryName[] =
 
 std::string GCMEncryptionProvider::ToDecryptionResultDetailsString(
     DecryptionResult result) {
-  switch(result) {
+  switch (result) {
     case DECRYPTION_RESULT_UNENCRYPTED:
       return "Message was not encrypted";
     case DECRYPTION_RESULT_DECRYPTED:

components/history/core/browser/android/android_urls_sql_handler.cc

@@ -51,14 +51,9 @@ bool AndroidURLsSQLHandler::Insert(HistoryAndBookmarkRow* row) {
 
 bool AndroidURLsSQLHandler::Delete(const TableIDRows& ids_set) {
   std::vector<URLID> ids;
-  for (TableIDRows::const_iterator id = ids_set.begin();
-       id != ids_set.end(); ++id)
-    ids.push_back(id->url_id);
-
-  if (!ids.size())
-    return true;
-
-  return android_urls_db_->DeleteAndroidURLRows(ids);
+  for (const auto& id : ids_set)
+    ids.push_back(id.url_id);
+  return ids.empty() || android_urls_db_->DeleteAndroidURLRows(ids);
 }
 
 }  // namespace history.

components/history/core/browser/history_backend.cc

@@ -102,7 +102,7 @@ MostVisitedURL MakeMostVisitedURL(const PageUsageData& page_data,
     mv.redirects.push_back(mv.url);
   } else {
     mv.redirects = redirects;
-    if (mv.redirects[mv.redirects.size() - 1] != mv.url) {
+    if (mv.redirects.back() != mv.url) {
       // The last url must be the target url.
       mv.redirects.push_back(mv.url);
     }

components/history/core/browser/url_database.cc

@@ -528,8 +528,7 @@ void URLDatabase::GetMostRecentKeywordSearchTerms(
   base::string16 lower_prefix = base::i18n::ToLower(prefix);
   // This magic gives us a prefix search.
   base::string16 next_prefix = lower_prefix;
-  next_prefix[next_prefix.size() - 1] =
-      next_prefix[next_prefix.size() - 1] + 1;
+  next_prefix.back() = next_prefix.back() + 1;
   statement.BindInt64(0, keyword_id);
   statement.BindString16(1, lower_prefix);
   statement.BindString16(2, next_prefix);

components/proximity_auth/remote_device_loader.cc

@@ -88,7 +88,7 @@ void RemoteDeviceLoader::OnPSKDerived(
       user_id_, unlock_key.friendly_device_name(), unlock_key.public_key(),
       bluetooth_type, bluetooth_address, psk, std::string()));
 
-  if (!remaining_unlock_keys_.size())
+  if (remaining_unlock_keys_.empty())
     callback_.Run(remote_devices_);
 }
 

components/safe_browsing_db/util.cc

@@ -403,8 +403,7 @@ void UrlToFullHashes(const GURL& url,
       // We may have /foo as path-prefix in the whitelist which should
       // also match with /foo/bar and /foo?bar.  Hence, for every path
       // that ends in '/' we also add the path without the slash.
-      if (include_whitelist_hashes && path.size() > 1 &&
-          path[path.size() - 1] == '/') {
+      if (include_whitelist_hashes && path.size() > 1 && path.back() == '/') {
         full_hashes->push_back(SBFullHashForString(
             host + path.substr(0, path.size() - 1)));
       }

components/sessions/core/tab_restore_service_helper.cc

@@ -138,22 +138,21 @@ std::vector<LiveTab*> TabRestoreServiceHelper::RestoreMostRecentEntry(
     LiveTabContext* context) {
   if (entries_.empty())
     return std::vector<LiveTab*>();
-
   return RestoreEntryById(context, entries_.front()->id, UNKNOWN);
 }
 
 TabRestoreService::Tab* TabRestoreServiceHelper::RemoveTabEntryById(
     SessionID::id_type id) {
-  Entries::iterator i = GetEntryIteratorById(id);
-  if (i == entries_.end())
-    return NULL;
+  Entries::iterator it = GetEntryIteratorById(id);
+  if (it == entries_.end())
+    return nullptr;
 
-  Entry* entry = *i;
+  Entry* entry = *it;
   if (entry->type != TabRestoreService::TAB)
-    return NULL;
+    return nullptr;
 
   Tab* tab = static_cast<Tab*>(entry);
-  entries_.erase(i);
+  entries_.erase(it);
   return tab;
 }
 
@@ -162,9 +161,10 @@ std::vector<LiveTab*> TabRestoreServiceHelper::RestoreEntryById(
     SessionID::id_type id,
     WindowOpenDisposition disposition) {
   Entries::iterator entry_iterator = GetEntryIteratorById(id);
-  if (entry_iterator == entries_.end())
+  if (entry_iterator == entries_.end()) {
     // Don't hoark here, we allow an invalid id.
     return std::vector<LiveTab*>();
+  }
 
   if (observer_)
     observer_->OnRestoreEntryById(id, entry_iterator);
@@ -186,7 +186,7 @@ std::vector<LiveTab*> TabRestoreServiceHelper::RestoreEntryById(
   std::vector<LiveTab*> live_tabs;
   if (entry->type == TabRestoreService::TAB) {
     Tab* tab = static_cast<Tab*>(entry);
-    LiveTab* restored_tab = NULL;
+    LiveTab* restored_tab = nullptr;
     context = RestoreTab(*tab, context, disposition, &restored_tab);
     live_tabs.push_back(restored_tab);
     context->ShowBrowserWindow();
@@ -225,28 +225,27 @@ std::vector<LiveTab*> TabRestoreServiceHelper::RestoreEntryById(
       for (std::vector<Tab>::iterator tab_i = window->tabs.begin();
            tab_i != window->tabs.end(); ++tab_i) {
         const Tab& tab = *tab_i;
-        if (tab.id == id) {
-          LiveTab* restored_tab = NULL;
-          context = RestoreTab(tab, context, disposition, &restored_tab);
-          live_tabs.push_back(restored_tab);
-          window->tabs.erase(tab_i);
-          // If restoring the tab leaves the window with nothing else, delete it
-          // as well.
-          if (!window->tabs.size()) {
-            entries_.erase(entry_iterator);
-            delete entry;
-          } else {
-            // Update the browser ID of the rest of the tabs in the window so if
-            // any one is restored, it goes into the same window as the tab
-            // being restored now.
-            UpdateTabBrowserIDs(tab.browser_id, context->GetSessionID().id());
-            for (std::vector<Tab>::iterator tab_j = window->tabs.begin();
-                 tab_j != window->tabs.end(); ++tab_j) {
-              (*tab_j).browser_id = context->GetSessionID().id();
-            }
-          }
-          break;
+        if (tab.id != id)
+          continue;
+
+        LiveTab* restored_tab = nullptr;
+        context = RestoreTab(tab, context, disposition, &restored_tab);
+        live_tabs.push_back(restored_tab);
+        window->tabs.erase(tab_i);
+        // If restoring the tab leaves the window with nothing else, delete it
+        // as well.
+        if (window->tabs.empty()) {
+          entries_.erase(entry_iterator);
+          delete entry;
+        } else {
+          // Update the browser ID of the rest of the tabs in the window so if
+          // any one is restored, it goes into the same window as the tab
+          // being restored now.
+          UpdateTabBrowserIDs(tab.browser_id, context->GetSessionID().id());
+          for (Tab& tab_j : window->tabs)
+            tab_j.browser_id = context->GetSessionID().id();
         }
+        break;
       }
     }
     context->ShowBrowserWindow();

components/sync_sessions/synced_session_tracker.cc

@@ -215,39 +215,36 @@ void SyncedSessionTracker::DeleteForeignTab(const std::string& session_tag,
 
 bool SyncedSessionTracker::DeleteOldSessionWindowIfNecessary(
     const SessionWindowWrapper& window_wrapper) {
-  if (!window_wrapper.owned) {
-    DVLOG(1) << "Deleting closed window "
-             << window_wrapper.window_ptr->window_id.id();
-    // Clear the tabs first, since we don't want the destructor to destroy
-    // them. Their deletion will be handled by DeleteOldSessionTabIfNecessary.
-    window_wrapper.window_ptr->tabs.clear();
-    delete window_wrapper.window_ptr;
-    return true;
-  }
-  return false;
+  if (window_wrapper.owned)
+    return false;
+
+  DVLOG(1) << "Deleting closed window "
+           << window_wrapper.window_ptr->window_id.id();
+  // Clear the tabs first, since we don't want the destructor to destroy
+  // them. Their deletion will be handled by DeleteOldSessionTabIfNecessary.
+  window_wrapper.window_ptr->tabs.clear();
+  delete window_wrapper.window_ptr;
+  return true;
 }
 
 bool SyncedSessionTracker::DeleteOldSessionTabIfNecessary(
     const SessionTabWrapper& tab_wrapper) {
-  if (!tab_wrapper.owned) {
-    if (VLOG_IS_ON(1)) {
-      sessions::SessionTab* tab_ptr = tab_wrapper.tab_ptr;
-      std::string title;
-      if (tab_ptr->navigations.size() > 0) {
-        title =
-            " (" +
-            base::UTF16ToUTF8(
-                tab_ptr->navigations[tab_ptr->navigations.size() - 1].title()) +
-            ")";
-      }
-      DVLOG(1) << "Deleting closed tab " << tab_ptr->tab_id.id() << title
-               << " from window " << tab_ptr->window_id.id();
+  if (tab_wrapper.owned)
+    return false;
+
+  if (VLOG_IS_ON(1)) {
+    sessions::SessionTab* tab_ptr = tab_wrapper.tab_ptr;
+    std::string title;
+    if (!tab_ptr->navigations.empty()) {
+      title =
+          " (" + base::UTF16ToUTF8(tab_ptr->navigations.back().title()) + ")";
     }
-    unmapped_tabs_.erase(tab_wrapper.tab_ptr);
-    delete tab_wrapper.tab_ptr;
-    return true;
+    DVLOG(1) << "Deleting closed tab " << tab_ptr->tab_id.id() << title
+             << " from window " << tab_ptr->window_id.id();
   }
-  return false;
+  unmapped_tabs_.erase(tab_wrapper.tab_ptr);
+  delete tab_wrapper.tab_ptr;
+  return true;
 }
 
 void SyncedSessionTracker::CleanupSession(const std::string& session_tag) {
@@ -400,15 +397,12 @@ sessions::SessionTab* SyncedSessionTracker::GetTabImpl(
       std::string title;
       if (tab_ptr->navigations.size() > 0) {
         title =
-            " (" +
-            base::UTF16ToUTF8(
-                tab_ptr->navigations[tab_ptr->navigations.size() - 1].title()) +
-            ")";
+            " (" + base::UTF16ToUTF8(tab_ptr->navigations.back().title()) + ")";
       }
       DVLOG(1) << "Getting "
                << (session_tag == local_session_tag_ ? "local session"
                                                      : session_tag)
-               << "'s seen tab " << tab_id << " at " << tab_ptr << title;
+               << "'s seen tab " << tab_id << " at " << tab_ptr << " " << title;
     }
   } else {
     tab_ptr = new sessions::SessionTab();

components/url_matcher/url_matcher.cc

@@ -513,30 +513,26 @@ URLMatcherCondition URLMatcherConditionFactory::CreateCondition(
   PatternSingletons::const_iterator iter =
       pattern_singletons->find(&search_pattern);
 
-  if (iter != pattern_singletons->end()) {
+  if (iter != pattern_singletons->end())
     return URLMatcherCondition(criterion, *iter);
-  } else {
-    StringPattern* new_pattern =
-        new StringPattern(pattern, id_counter_++);
-    pattern_singletons->insert(new_pattern);
-    return URLMatcherCondition(criterion, new_pattern);
-  }
+
+  StringPattern* new_pattern = new StringPattern(pattern, id_counter_++);
+  pattern_singletons->insert(new_pattern);
+  return URLMatcherCondition(criterion, new_pattern);
 }
 
 std::string URLMatcherConditionFactory::CanonicalizeHostSuffix(
     const std::string& suffix) const {
-  if (!suffix.empty() && suffix[suffix.size() - 1] == '.')
-    return suffix;
-  else
-    return suffix + ".";
+  if (suffix.empty())
+    return ".";
+  return suffix.back() == '.' ? suffix : suffix + ".";
 }
 
 std::string URLMatcherConditionFactory::CanonicalizeHostPrefix(
     const std::string& prefix) const {
-  if (!prefix.empty() && prefix[0] == '.')
-    return prefix;
-  else
-    return "." + prefix;
+  if (prefix.empty())
+    return ".";
+  return prefix[0] == '.' ? prefix : "." + prefix;
 }
 
 std::string URLMatcherConditionFactory::CanonicalizeHostname(

components/webcrypto/algorithms/ecdh_unittest.cc

@@ -219,7 +219,7 @@ TEST_F(WebCryptoEcdhTest, DeriveKeyHmac19Bits) {
             ExportKey(blink::WebCryptoKeyFormatRaw, derived_key, &raw_key));
   EXPECT_EQ(3u, raw_key.size());
   // The last 7 bits of the key should be zero.
-  EXPECT_EQ(0, raw_key[raw_key.size() - 1] & 0x1f);
+  EXPECT_EQ(0, raw_key.back() & 0x1f);
 }
 
 // Derive an HMAC key with no specified length (just the hash of SHA-256).

components/webcrypto/algorithms/util.cc

@@ -47,7 +47,7 @@ void TruncateToBitLength(size_t length_bits, std::vector<uint8_t>* bytes) {
 
   // Zero any "unused bits" in the final byte.
   if (remainder_bits)
-    (*bytes)[bytes->size() - 1] &= ~((0xFF) >> remainder_bits);
+    bytes->back() &= ~((0xFF) >> remainder_bits);
 }
 
 Status CheckKeyCreationUsages(blink::WebCryptoKeyUsageMask all_possible_usages,