A few fixes for image search:

chrome/browser/renderer_host/chrome_render_view_host_observer.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/renderer_host/chrome_render_view_host_observer.h"
 
 #include <vector>
 
 #include "base/command_line.h"
 #include "base/strings/stringprintf.h"
@@ skipping 188 matching lines @@
 #if defined(OS_WIN) && defined(USE_AURA)
     base::win::DismissVirtualKeyboard();
 #endif
   }
 }
 
 // Handles the image thumbnail for the context node, composes a image search
 // request based on the received thumbnail and opens the request in a new tab.
 void ChromeRenderViewHostObserver::OnRequestThumbnailForContextNodeACK(
     const SkBitmap& bitmap) {
-  const int kDefaultQualityForImageSearch = 90;
   WebContents* web_contents =
       WebContents::FromRenderViewHost(render_view_host());
-  if (!web_contents)
+  const TemplateURL* const default_provider =
+      TemplateURLServiceFactory::GetForProfile(profile_)->
+          GetDefaultSearchProvider();
+  if (!web_contents || !default_provider)
     return;
 
+  const int kDefaultQualityForImageSearch = 90;
   std::vector<unsigned char> data;
   if (!gfx::JPEGCodec::Encode(
       reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0)),
       gfx::JPEGCodec::FORMAT_SkBitmap, bitmap.width(), bitmap.height(),
       static_cast<int>(bitmap.rowBytes()), kDefaultQualityForImageSearch,
       &data))
     return;
 
-  const TemplateURL* const default_provider =
-      TemplateURLServiceFactory::GetForProfile(profile_)->
-          GetDefaultSearchProvider();
-  DCHECK(default_provider);
   TemplateURLRef::SearchTermsArgs search_args =
       TemplateURLRef::SearchTermsArgs(base::string16());
-  search_args.image_thumbnail_content = std::string(data.begin(),
-                                                    data.end());
+  search_args.image_thumbnail_content = std::string(data.begin(), data.end());
   // TODO(jnd): Add a method in WebContentsViewDelegate to get the image URL
   // from the ContextMenuParams which creates current context menu.
   search_args.image_url = GURL();
   TemplateURLRef::PostContent post_content;
   GURL result(default_provider->image_url_ref().ReplaceSearchTerms(
       search_args, &post_content));
   if (!result.is_valid())
     return;
 
   OpenURLParams open_url_params(result, content::Referrer(), NEW_FOREGROUND_TAB,
                                 content::PAGE_TRANSITION_LINK, false);
   const std::string& content_type = post_content.first;
-  std::string& post_data = post_content.second;
-  if (!post_data.empty()) {
+  std::string* post_data = &post_content.second;
+  if (!post_data->empty()) {
     DCHECK(!content_type.empty());
     open_url_params.uses_post = true;
     open_url_params.browser_initiated_post_data =
-        base::RefCountedString::TakeString(&post_data);
+        base::RefCountedString::TakeString(post_data);
     open_url_params.extra_headers += base::StringPrintf(
         "%s: %s\r\n", net::HttpRequestHeaders::kContentType,
         content_type.c_str());
   }
-
   web_contents->OpenURL(open_url_params);
 }