Add latency measurement system

cc/gl_renderer.cc

Index: cc/gl_renderer.cc
diff --git a/cc/gl_renderer.cc b/cc/gl_renderer.cc
index ad26183a4879525b2c2d128a42dfedbc16a677a8..685ee3f486b84ccc360267f4f37babb39d531ec4 100644
--- a/cc/gl_renderer.cc
+++ b/cc/gl_renderer.cc
@@ -118,6 +118,8 @@ bool GLRenderer::initialize()
     if (m_capabilities.usingGpuMemoryManager)
         m_context->setMemoryAllocationChangedCallbackCHROMIUM(this);
 
+    m_context->setLatencyInfoCallbackCHROMIUM(this);
+
     m_capabilities.usingDiscardBackbuffer = extensions.count("GL_CHROMIUM_discard_backbuffer");
 
     m_capabilities.usingEglImage = extensions.count("GL_OES_EGL_image_external");
@@ -1271,6 +1273,16 @@ void GLRenderer::onSwapBuffersComplete()
     m_client->onSwapBuffersComplete();
 }
 
+void GLRenderer::setLatencyInfo(const WebKit::WebLatencyInfoImpl& latency_info)
+{
+    m_context->setLatencyInfoCHROMIUM(static_cast<const WebKit::WebLatencyInfo&>(latency_info));
+}
+
+void GLRenderer::onReceivedLatencyInfo(const WebKit::WebLatencyInfo& latency_info)
+{
+    m_client->onReceivedLatencyInfo(static_cast<const WebKit::WebLatencyInfoImpl&>(latency_info));
+}
+
 void GLRenderer::onMemoryAllocationChanged(WebGraphicsMemoryAllocation allocation)
 {
     // Just ignore the memory manager when it says to set the limit to zero