diff --git a/pdf/document_loader.cc b/pdf/document_loader.cc
index 03e82edbf4582b..165fffe88682e7 100644
--- a/pdf/document_loader.cc
+++ b/pdf/document_loader.cc
@@ -67,6 +67,15 @@ std::string GetMultiPartBoundary(const std::string& headers) {
   return std::string();
 }
 
+bool IsValidContentType(const std::string& type) {
+  return (EndsWith(type, "/pdf", false) ||
+          EndsWith(type, ".pdf", false) ||
+          EndsWith(type, "/x-pdf", false) ||
+          EndsWith(type, "/*", false) ||
+          EndsWith(type, "/acrobat", false) ||
+          EndsWith(type, "/unknown", false));
+}
+
 }  // namespace
 
 DocumentLoader::Client::~Client() {
@@ -106,7 +115,15 @@ bool DocumentLoader::Init(const pp::URLLoader& loader,
   uint32_t content_length = 0;
   std::string type;
   std::string disposition;
-  if (!response_headers.empty()) {
+
+  // This happens for PDFs not loaded from http(s) sources.
+  if (response_headers == "Content-Type: text/plain") {
+    if (!StartsWithASCII(url, "http://", false) &&
+        !StartsWithASCII(url, "https://", false)) {
+      type = "application/pdf";
+    }
+  }
+  if (type.empty() && !response_headers.empty()) {
     net::HttpUtil::HeadersIterator it(response_headers.begin(),
                                       response_headers.end(), "\n");
     while (it.GetNext()) {
@@ -128,18 +145,10 @@ bool DocumentLoader::Init(const pp::URLLoader& loader,
       }
     }
   }
-  if (!type.empty() &&
-      !EndsWith(type, "/pdf", false) &&
-      !EndsWith(type, ".pdf", false) &&
-      !EndsWith(type, "/x-pdf", false) &&
-      !EndsWith(type, "/*", false) &&
-      !EndsWith(type, "/acrobat", false) &&
-      !EndsWith(type, "/unknown", false)) {
+  if (!type.empty() && !IsValidContentType(type))
     return false;
-  }
-  if (StartsWithASCII(disposition, "attachment", false)) {
+  if (StartsWithASCII(disposition, "attachment", false))
     return false;
-  }
 
   if (content_length > 0)
     chunk_stream_.Preallocate(content_length);
diff --git a/pdf/out_of_process_instance.cc b/pdf/out_of_process_instance.cc
index c75d04af27f160..b457b648dc400b 100644
--- a/pdf/out_of_process_instance.cc
+++ b/pdf/out_of_process_instance.cc
@@ -342,9 +342,9 @@ bool OutOfProcessInstance::Init(uint32_t argc,
 
   text_input_.reset(new pp::TextInput_Dev(this));
 
-  const char* stream_url = NULL;
-  const char* original_url = NULL;
-  const char* headers = NULL;
+  const char* stream_url = nullptr;
+  const char* original_url = nullptr;
+  const char* headers = nullptr;
   bool is_material = false;
   for (uint32_t i = 0; i < argc; ++i) {
     if (strcmp(argn[i], "src") == 0)
@@ -362,12 +362,6 @@ bool OutOfProcessInstance::Init(uint32_t argc,
   else
     background_color_ = kBackgroundColor;
 
-  // TODO(raymes): This is a hack to ensure that if no headers are passed in
-  // then we get the right MIME type. When the in process plugin is removed we
-  // can fix the document loader properly and remove this hack.
-  if (!headers || strcmp(headers, "") == 0)
-    headers = "content-type: application/pdf";
-
   if (!original_url)
     return false;
 
@@ -443,7 +437,7 @@ void OutOfProcessInstance::HandleMessage(const pp::Var& message) {
     preview_engine_.reset();
     engine_.reset(PDFEngine::Create(this));
     engine_->SetGrayscale(dict.Get(pp::Var(kJSPrintPreviewGrayscale)).AsBool());
-    engine_->New(url_.c_str());
+    engine_->New(url_.c_str(), nullptr /* empty header */);
 
     print_preview_page_count_ =
         std::max(dict.Get(pp::Var(kJSPrintPreviewPageCount)).AsInt(), 0);
@@ -908,7 +902,7 @@ void OutOfProcessInstance::UpdateCursor(PP_CursorType_Dev cursor) {
   }
 
   cursor_interface->SetCursor(
-      pp_instance(), cursor_, pp::ImageData().pp_resource(), NULL);
+      pp_instance(), cursor_, pp::ImageData().pp_resource(), nullptr);
 }
 
 void OutOfProcessInstance::UpdateTickMarks(
@@ -1170,7 +1164,7 @@ void OutOfProcessInstance::PreviewDocumentLoadComplete() {
   if (print_preview_page_count_ == 0)
     return;
 
-  if (preview_pages_info_.size())
+  if (!preview_pages_info_.empty())
     LoadAvailablePreviewPage();
 }
 
@@ -1203,7 +1197,7 @@ void OutOfProcessInstance::PreviewDocumentLoadFailed() {
   preview_document_load_state_ = LOAD_STATE_FAILED;
   preview_pages_info_.pop();
 
-  if (preview_pages_info_.size())
+  if (!preview_pages_info_.empty())
     LoadAvailablePreviewPage();
 }
 
@@ -1353,7 +1347,7 @@ void OutOfProcessInstance::AppendBlankPrintPreviewPages() {
   if (print_preview_page_count_ == 0)
     return;
   engine_->AppendBlankPages(print_preview_page_count_);
-  if (preview_pages_info_.size() > 0)
+  if (!preview_pages_info_.empty())
     LoadAvailablePreviewPage();
 }
 
@@ -1386,7 +1380,7 @@ void OutOfProcessInstance::ProcessPreviewPageInfo(const std::string& url,
 }
 
 void OutOfProcessInstance::LoadAvailablePreviewPage() {
-  if (preview_pages_info_.size() <= 0 ||
+  if (preview_pages_info_.empty() ||
       document_load_state_ != LOAD_STATE_COMPLETE) {
     return;
   }
diff --git a/pdf/out_of_process_instance.h b/pdf/out_of_process_instance.h
index a458a924f87e28..8a3de66e2e7ba4 100644
--- a/pdf/out_of_process_instance.h
+++ b/pdf/out_of_process_instance.h
@@ -167,12 +167,6 @@ class OutOfProcessInstance : public pp::Instance,
   // frame's origin.
   pp::URLLoader CreateURLLoaderInternal();
 
-  // Figure out the initial page to display based on #page=N and #nameddest=foo
-  // in the |url_|.
-  // Returns -1 if there is no valid fragment. The returned value is 0-based,
-  // whereas page=N is 1-based.
-  int GetInitialPage(const std::string& url);
-
   void FormDidOpen(int32_t result);
 
   std::string GetLocalizedString(PP_ResourceString id);
@@ -338,6 +332,8 @@ class OutOfProcessInstance : public pp::Instance,
 
   // The background color of the PDF viewer.
   uint32 background_color_;
+
+  DISALLOW_COPY_AND_ASSIGN(OutOfProcessInstance);
 };
 
 }  // namespace chrome_pdf
diff --git a/pdf/pdf_engine.h b/pdf/pdf_engine.h
index e99ab47ed878b6..857db88728e910 100644
--- a/pdf/pdf_engine.h
+++ b/pdf/pdf_engine.h
@@ -184,11 +184,10 @@ class PDFEngine {
   static PDFEngine* Create(Client* client);
 
   virtual ~PDFEngine() {}
+
   // Most of these functions are similar to the Pepper functions of the same
   // name, so not repeating the description here unless it's different.
-  virtual bool New(const char* url) = 0;
-  virtual bool New(const char* url,
-                   const char* headers) = 0;
+  virtual bool New(const char* url, const char* headers) = 0;
   virtual void PageOffsetUpdated(const pp::Point& page_offset) = 0;
   virtual void PluginSizeUpdated(const pp::Size& size) = 0;
   virtual void ScrolledToXPosition(int position) = 0;
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index f9feec8e0a7ed2..4b279462043f0e 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -941,8 +941,8 @@ FPDF_FILEHANDLER* PDFiumEngine::Form_OpenFile(FPDF_FORMFILLINFO* param,
     url_str =
         base::UTF16ToUTF8(reinterpret_cast<const base::char16*>(url));
   }
-  //  TODO: need to implement open file from the url
-  //  Use a file path for the ease of testing
+  // TODO: need to implement open file from the url
+  // Use a file path for the ease of testing
   FILE* file = fopen(XFA_TESTFILE("tem.txt"), mode);
   FPDF_FILE* file_wrapper = new FPDF_FILE;
   file_wrapper->file = file;
@@ -992,17 +992,11 @@ void PDFiumEngine::AddSegment(FX_DOWNLOADHINTS* param,
   return download_hints->loader->RequestData(offset, size);
 }
 
-bool PDFiumEngine::New(const char* url) {
-  url_ = url;
-  headers_ = std::string();
-  return true;
-}
-
 bool PDFiumEngine::New(const char* url,
                        const char* headers) {
   url_ = url;
   if (!headers)
-    headers_ = std::string();
+    headers_.clear();
   else
     headers_ = headers;
   return true;
@@ -1243,7 +1237,7 @@ void PDFiumEngine::FinishLoadingDocument() {
     FORM_DoPageAAction(new_page, form_, FPDFPAGE_AACTION_OPEN);
   }
 
-  if (doc_) // This can only happen if loading |doc_| fails.
+  if (doc_)  // This can only happen if loading |doc_| fails.
     client_->DocumentLoadComplete(pages_.size());
 }
 
@@ -2003,8 +1997,8 @@ void PDFiumEngine::StartFind(const char* text, bool case_sensitive) {
 
   if (pages_[current_page]->available()) {
     base::string16 str = base::UTF8ToUTF16(text);
-    // Don't use PDFium to search for now, since it doesn't support unicode text.
-    // Leave the code for now to avoid bit-rot, in case it's fixed later.
+    // Don't use PDFium to search for now, since it doesn't support unicode
+    // text. Leave the code for now to avoid bit-rot, in case it's fixed later.
     if (0) {
       SearchUsingPDFium(
           str, case_sensitive, first_search, character_to_start_searching_from,
@@ -2483,7 +2477,7 @@ bool PDFiumEngine::GetPageSizeAndUniformity(pp::Size* size) {
 }
 
 void PDFiumEngine::AppendBlankPages(int num_pages) {
-  DCHECK(num_pages != 0);
+  DCHECK_NE(num_pages, 0);
 
   if (!doc_)
     return;
diff --git a/pdf/pdfium/pdfium_engine.h b/pdf/pdfium/pdfium_engine.h
index 0c9ecd92637494..480a6e8e94abdc 100644
--- a/pdf/pdfium/pdfium_engine.h
+++ b/pdf/pdfium/pdfium_engine.h
@@ -46,9 +46,7 @@ class PDFiumEngine : public PDFEngine,
   virtual ~PDFiumEngine();
 
   // PDFEngine implementation.
-  virtual bool New(const char* url);
-  virtual bool New(const char* url,
-                   const char* headers);
+  virtual bool New(const char* url, const char* headers);
   virtual void PageOffsetUpdated(const pp::Point& page_offset);
   virtual void PluginSizeUpdated(const pp::Size& size);
   virtual void ScrolledToXPosition(int position);