Implement transform/clip support for Android WebView.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index 15766c4ef0dba0b4b68870090d4f1e286e646f15..7275bf53cc028d414a8102b4a5aa1b791cb8a903 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -2374,7 +2374,7 @@ bool GLRenderer::BindFramebufferToTexture(DrawingFrame* frame,
   DCHECK(context_->checkFramebufferStatus(GL_FRAMEBUFFER) ==
          GL_FRAMEBUFFER_COMPLETE || IsContextLost());
 
-  InitializeMatrices(frame, framebuffer_rect, false);
+  InitializeMatrices(frame, gfx::Vector2d(), framebuffer_rect, false);
   SetDrawViewportSize(framebuffer_rect.size());
 
   return true;
@@ -2400,7 +2400,10 @@ void GLRenderer::SetScissorTestRect(gfx::Rect scissor_rect) {
 void GLRenderer::SetDrawViewportSize(gfx::Size viewport_size) {
   current_framebuffer_size_ = viewport_size;
   GLC(context_,
-      context_->viewport(0, 0, viewport_size.width(), viewport_size.height()));
+      context_->viewport(client_->DeviceViewportOffset().x(),
+                         client_->DeviceViewportOffset().y(),
+                         viewport_size.width(),
+                         viewport_size.height()));
 }
 
 bool GLRenderer::MakeContextCurrent() { return context_->makeContextCurrent(); }