gpu: gpu decoder sets viewport size same to the size of the default framebuffer.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 8c24d3cd1df5f8e04a458d173ec5106f5d3971bd..353cb9f5bdb245942d6e16eb4bd0fcf69e0a79a3 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -585,7 +585,7 @@ class GLES2DecoderImpl : public GLES2Decoder,
   bool Initialize(const scoped_refptr<gfx::GLSurface>& surface,
                   const scoped_refptr<gfx::GLContext>& context,
                   bool offscreen,
-                  const gfx::Size& size,
+                  const gfx::Size& offscreen_size,
                   const DisallowedFeatures& disallowed_features,
                   const std::vector<int32>& attribs) override;
   void Destroy(bool have_context) override;
@@ -2434,7 +2434,7 @@ bool GLES2DecoderImpl::Initialize(
     const scoped_refptr<gfx::GLSurface>& surface,
     const scoped_refptr<gfx::GLContext>& context,
     bool offscreen,
-    const gfx::Size& size,
+    const gfx::Size& offscreen_size,
     const DisallowedFeatures& disallowed_features,
     const std::vector<int32>& attribs) {
   TRACE_EVENT0("gpu", "GLES2DecoderImpl::Initialize");
@@ -2675,12 +2675,15 @@ bool GLES2DecoderImpl::Initialize(
 
     // Allocate the render buffers at their initial size and check the status
     // of the frame buffers is okay.
-    if (!ResizeOffscreenFrameBuffer(size)) {
+    if (!ResizeOffscreenFrameBuffer(offscreen_size)) {
       LOG(ERROR) << "Could not allocate offscreen buffer storage.";
       Destroy(true);
       return false;
     }
 
+    state_.viewport_width = offscreen_size.width();
+    state_.viewport_height = offscreen_size.height();
+
     // Allocate the offscreen saved color texture.
     DCHECK(offscreen_saved_color_format_);
     offscreen_saved_color_texture_->AllocateStorage(
@@ -2720,6 +2723,9 @@ bool GLES2DecoderImpl::Initialize(
       glGetIntegerv(GL_STENCIL_BITS, &v);
       back_buffer_has_stencil_ = attrib_parser.stencil_size != 0 && v > 0;
     }
+
+    state_.viewport_width = surface->GetSize().width();
+    state_.viewport_height = surface->GetSize().height();
   }
 
   // OpenGL ES 2.0 implicitly enables the desktop GL capability
@@ -2742,9 +2748,6 @@ bool GLES2DecoderImpl::Initialize(
     return false;
   }
 
-  state_.viewport_width = size.width();
-  state_.viewport_height = size.height();
-
   GLint viewport_params[4] = { 0 };
   glGetIntegerv(GL_MAX_VIEWPORT_DIMS, viewport_params);
   viewport_max_width_ = viewport_params[0];