Add Async API unittests to readback format.

content/common/gpu/client/gl_helper.cc

Index: content/common/gpu/client/gl_helper.cc
diff --git a/content/common/gpu/client/gl_helper.cc b/content/common/gpu/client/gl_helper.cc
index 7da9389bc10ef9c31f001eb5757a344f3ba69f30..96e483f1f0eb00a12b3f91a5ee890dbfc50e2401 100644
--- a/content/common/gpu/client/gl_helper.cc
+++ b/content/common/gpu/client/gl_helper.cc
@@ -136,6 +136,12 @@ class GLHelper::CopyTextureToImpl
                            unsigned char* out,
                            SkBitmap::Config format);
 
+  void ReadbackTextureAsync(GLuint texture,
+                            const gfx::Size& dst_size,
+                            unsigned char* out,
+                            SkBitmap::Config config,
+                            const base::Callback<void(bool)>& callback);
+
   // Reads back bytes from the currently bound frame buffer.
   // Note that dst_size is specified in bytes, not pixels.
   void ReadbackAsync(const gfx::Size& dst_size,
@@ -473,6 +479,31 @@ void GLHelper::CopyTextureToImpl::ReadbackTextureSync(GLuint texture,
                   out);
 }
 
+void GLHelper::CopyTextureToImpl::ReadbackTextureAsync(
+    GLuint texture,
+    const gfx::Size& dst_size,
+    unsigned char* out,
+    SkBitmap::Config config,
+    const base::Callback<void(bool)>& callback) {

[piman, 2014/01/23 20:43:57]

Can you add DCHECKs on the supported formats?

[sivag, 2014/01/24 15:56:40]

Done.

+  ScopedFramebuffer dst_framebuffer(gl_);
+  ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(gl_,
+                                                             dst_framebuffer);
+  ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, texture);
+  gl_->FramebufferTexture2D(GL_FRAMEBUFFER,
+                            GL_COLOR_ATTACHMENT0,
+                            GL_TEXTURE_2D,
+                            texture,
+                            0);
+  int readback_config_rgb565 = (config ==  SkBitmap::kRGB_565_Config);
+  int bytes_per_pixel = readback_config_rgb565 ? 2 : 4;
+  ReadbackAsync(dst_size,
+                dst_size.width() * bytes_per_pixel,
+                dst_size.width() * bytes_per_pixel,
+                out,
+                readback_config_rgb565,

[piman, 2014/01/23 20:43:57]

This would change when rebasing on top of your
https://codereview.chromium.org/143683003/ , right?

If you're using git, what you can do is:
- rebase the branch for this CL on top of the branch for
https://codereview.chromium.org/143683003/
- use git set-upstream-to to ensure this branch is tracking the other branch

Then git cl upload will upload the diff between this branch and the other branch
(as opposed to origin/master), and will give the correct diff.

[sivag, 2014/01/24 15:56:40]

Thanks for sharing this tip :). As my branches are in different workspace i
tried this but finally due to some issue i did the rebase after the patch got
commited. I Will definitely use this tip When i face the same situation again. 

+                callback);
+}
+
 GLuint GLHelper::CopyTextureToImpl::CopyAndScaleTexture(
     GLuint src_texture,
     const gfx::Size& src_size,
@@ -607,6 +638,20 @@ void GLHelper::ReadbackTextureSync(GLuint texture,
   copy_texture_to_impl_->ReadbackTextureSync(texture, src_rect, out, format);
 }
 
+void GLHelper::ReadbackTextureAsync(
+    GLuint texture,
+    const gfx::Size& dst_size,
+    unsigned char* out,
+    SkBitmap::Config config,
+    const base::Callback<void(bool)>& callback) {
+  InitCopyTextToImpl();
+  copy_texture_to_impl_->ReadbackTextureAsync(texture,
+                                              dst_size,
+                                              out,
+                                              config,
+                                              callback);
+}
+
 GLuint GLHelper::CopyTexture(GLuint texture, const gfx::Size& size) {
   InitCopyTextToImpl();
   return copy_texture_to_impl_->CopyAndScaleTexture(