WIP: Plumbing input event latency reporting through Mus GPU.

ui/latency/latency_info.h

Index: ui/latency/latency_info.h
diff --git a/ui/latency/latency_info.h b/ui/latency/latency_info.h
index f34e09ac8ea47f67560820c47c1ed3e261576b0e..a122b0160fc18b0ea53e8d6434ff8d9537d2d756 100644
--- a/ui/latency/latency_info.h
+++ b/ui/latency/latency_info.h
@@ -75,9 +75,10 @@ enum LatencyComponentType {
   TAB_SHOW_COMPONENT,
   // Timestamp when the frame is swapped in renderer.
   INPUT_EVENT_LATENCY_RENDERER_SWAP_COMPONENT,
-  // Timestamp of when the browser process receives a buffer swap notification
-  // from the renderer.
-  INPUT_EVENT_BROWSER_RECEIVED_RENDERER_SWAP_COMPONENT,
+  // Timestamp of when the display compositor receives a compositor frame from
+  // the renderer.
+  // Display compositor can be either in the browser process or in Mus.
+  DISPLAY_COMPOSITOR_RECEIVED_FRAME_COMPONENT,
   // Timestamp of when the gpu service began swap buffers, unlike
   // INPUT_EVENT_LATENCY_TERMINATED_FRAME_SWAP_COMPONENT which measures after.
   INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT,
@@ -112,6 +113,8 @@ enum SourceEventType {
   SOURCE_EVENT_TYPE_LAST = OTHER,
 };
 
+const char* GetComponentName(ui::LatencyComponentType type);
+
 class LatencyInfo {
  public:
   struct LatencyComponent {
@@ -193,6 +196,12 @@ class LatencyInfo {
                    int64_t id,
                    LatencyComponent* output) const;
 
+  // Returns true if a component with |type| is found in the latency component.
+  // The first such component (when iterating over latency_components_) is
+  // stored to |output| if |output| is not NULL. Returns false if no such
+  // component is found.
+  bool FindLatency(LatencyComponentType type, LatencyComponent* output) const;
+
   void RemoveLatency(LatencyComponentType type);
 
   // Returns true if there is still room for keeping the |input_coordinate|,
@@ -256,6 +265,12 @@ class LatencyInfo {
 #endif
 };
 
+// This is declared here for use in gtest-based unit tests, but is defined in
+// //ui/latency:test_support target.
+// Without this the default PrintTo template in gtest tries to pass LatencyInfo
+// by value, which leads to an alignment compile error on Windows.
+void PrintTo(const LatencyInfo& latency, ::std::ostream* os);
+
 }  // namespace ui
 
 #endif  // UI_LATENCY_LATENCY_INFO_H_