Enable texture readback support for Android

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 775a651e76451422630cc2dc61299c4606dbeae5..b733218ed3ca9ebad08d15c8de0c092e4dc9f361 100644
--- a/content/common/gpu/client/gl_helper.cc
+++ b/content/common/gpu/client/gl_helper.cc
@@ -263,7 +263,13 @@ class GLHelper::CopyTextureToImpl {
                      unsigned char* out,
                      const base::Callback<void(bool)>& callback);
 
-  WebKit::WebGLId CopyTexture(WebGLId src_texture, const gfx::Size& size);
+  void SyncCopyRawTextureTo(WebGLId texture,
+                            const gfx::Size& size,
+                            unsigned char* out);
+
+  WebKit::WebGLId CopyTexture(WebGLId texture,
+                              const gfx::Size& src_size,
+                              const gfx::Size& dst_size);
 
  private:
   // A single request to CopyTextureTo.
@@ -517,12 +523,32 @@ void GLHelper::CopyTextureToImpl::CopyTextureTo(
                  base::MessageLoopProxy::current()));
 }
 
+void GLHelper::CopyTextureToImpl::SyncCopyRawTextureTo(WebGLId texture,
+                                                       const gfx::Size& size,
+                                                       unsigned char* out) {
+  ScopedFramebuffer dst_framebuffer(context_, context_->createFramebuffer());
+  ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(
+      context_, dst_framebuffer);
+  ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(context_, texture);
+  context_->framebufferTexture2D(GL_FRAMEBUFFER,
+                                 GL_COLOR_ATTACHMENT0,
+                                 GL_TEXTURE_2D,
+                                 texture,
+                                 0);
+  context_->readPixels(0,
+                       0,
+                       size.width(),
+                       size.height(),
+                       GL_RGBA,
+                       GL_UNSIGNED_BYTE,
+                       out);
+}
+
 WebKit::WebGLId GLHelper::CopyTextureToImpl::CopyTexture(
     WebGLId src_texture,
-    const gfx::Size& size) {
-  if (!context_for_thread_)
-    return 0;
-  return ScaleTexture(src_texture, size, gfx::Rect(size), size);
+    const gfx::Size& src_size,
+    const gfx::Size& dst_size) {
+  return ScaleTexture(src_texture, src_size, gfx::Rect(src_size), dst_size);
 }
 
 void GLHelper::CopyTextureToImpl::ReadBackFramebuffer(
@@ -673,10 +699,27 @@ void GLHelper::CopyTextureTo(WebGLId src_texture,
                                        callback);
 }
 
+void GLHelper::SyncCopyRawTextureTo(WebKit::WebGLId texture,
+                                    const gfx::Size& size,
+                                    unsigned char* out) {
+  InitCopyTextToImpl();
+  copy_texture_to_impl_->SyncCopyRawTextureTo(texture,
+                                              size,
+                                              out);
+}
+
 WebKit::WebGLId GLHelper::CopyTexture(WebKit::WebGLId texture,
                                       const gfx::Size& size) {
+  return CopyTexture(texture,
+                     size,
+                     size);
+}
+
+WebKit::WebGLId GLHelper::CopyTexture(WebKit::WebGLId texture,
+                                      const gfx::Size& src_size,
+                                      const gfx::Size& dst_size) {
   InitCopyTextToImpl();
-  return copy_texture_to_impl_->CopyTexture(texture, size);
+  return copy_texture_to_impl_->CopyTexture(texture, src_size, dst_size);
 }
 
 WebGLId GLHelper::CompileShaderFromSource(