Allow CopyFromBackingStore to fallback to copying from the renderer side if the accelerated surface…

chrome/browser/extensions/api/tabs/tabs_api.cc

Index: chrome/browser/extensions/api/tabs/tabs_api.cc
diff --git a/chrome/browser/extensions/api/tabs/tabs_api.cc b/chrome/browser/extensions/api/tabs/tabs_api.cc
index 2a4e565039e1e542c29228befa4fc4d0117cfdf5..aed504c88938571c1cf4f8741f7b434ea53d7b93 100644
--- a/chrome/browser/extensions/api/tabs/tabs_api.cc
+++ b/chrome/browser/extensions/api/tabs/tabs_api.cc
@@ -45,7 +45,6 @@
 #include "chrome/browser/ui/extensions/shell_window.h"
 #include "chrome/browser/ui/host_desktop.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
-#include "chrome/browser/ui/snapshot_tab_helper.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/window_sizer/window_sizer.h"
 #include "chrome/browser/web_applications/web_app.h"
@@ -1744,49 +1743,14 @@ bool TabsCaptureVisibleTabFunction::RunImpl() {
 void TabsCaptureVisibleTabFunction::CopyFromBackingStoreComplete(
     bool succeeded,
     const SkBitmap& bitmap) {
-  if (succeeded) {
-    VLOG(1) << "captureVisibleTab() got image from backing store.";
-    SendResultFromBitmap(bitmap);
-    return;
-  }
-
-  WebContents* web_contents = NULL;
-  if (!GetTabToCapture(&web_contents)) {
+  if (!succeeded) {
     error_ = keys::kInternalVisibleTabCaptureError;
     SendResponse(false);
     return;
   }
 
-  // Ask the renderer for a snapshot of the tab.
-  registrar_.Add(this,
-                 chrome::NOTIFICATION_TAB_SNAPSHOT_TAKEN,
-                 content::Source<WebContents>(web_contents));
-  AddRef();  // Balanced in TabsCaptureVisibleTabFunction::Observe().
-  SnapshotTabHelper::FromWebContents(web_contents)->CaptureSnapshot();
-}
-
-// If a backing store was not available in
-// TabsCaptureVisibleTabFunction::RunImpl, than the renderer was asked for a
-// snapshot.  Listen for a notification that the snapshot is available.
-void TabsCaptureVisibleTabFunction::Observe(
-    int type,
-    const content::NotificationSource& source,
-    const content::NotificationDetails& details) {
-  DCHECK(type == chrome::NOTIFICATION_TAB_SNAPSHOT_TAKEN);
-
-  const SkBitmap *screen_capture =
-      content::Details<const SkBitmap>(details).ptr();
-  const bool error = screen_capture->empty();
-
-  if (error) {
-    error_ = keys::kInternalVisibleTabCaptureError;
-    SendResponse(false);
-  } else {
-    VLOG(1) << "captureVisibleTab() got image from renderer.";
-    SendResultFromBitmap(*screen_capture);
-  }
-
-  Release();  // Balanced in TabsCaptureVisibleTabFunction::RunImpl().
+  VLOG(1) << "captureVisibleTab() got image.";
+  SendResultFromBitmap(bitmap);

[Sam Kerner (Chrome), 2013/03/18 13:49:51]

It has been a while since I was in this code.  Is the backing store guaranteed
to give an image if it is possible to get one?  I wrote the fallback path you
removed because at the time, the backing store was an LRU cache of bitmaps.  The
cache had limited size, so that a miss was common for user with many tabs open.

 }
 
 // Turn a bitmap of the screen into an image, set that image as the result,