Support InputMethodManager#updateCursorAnchorInfo for Android 5.0

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 592a57c0c1d3a076f4b8354c9affead6d7f5bdd3..702302990d37c6ad715f6aa13731639c575b1a8c 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -87,6 +87,7 @@
 
 #if defined(OS_ANDROID)
 #include <android/keycodes.h>
+#include "base/android/build_info.h"
 #include "content/renderer/android/synchronous_compositor_factory.h"
 #include "content/renderer/android/synchronous_compositor_filter.h"
 #include "content/renderer/android/synchronous_compositor_output_surface.h"
@@ -1748,9 +1749,9 @@ ui::TextInputType RenderWidget::GetTextInputType() {
 
 void RenderWidget::UpdateCompositionInfo(bool should_update_range) {

[jdduke (slow), 2016/02/24 04:00:45]

The problem is, this method isn't just called when the compositon is updated. It
appears to be called at the start of each compositor frame (see
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/r...
and
https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/r...).

It's possible there are some clever early-out optimizations here and there, but
as it stands this is called way too frequently for low-end devices (perhaps even
high-end devices). We might need a similar compositor thread optimization as we
have now for the composited selection bounds updated.

 #if defined(OS_ANDROID)
-// TODO(yukawa): Start sending character bounds when the browser side
-// implementation becomes ready (crbug.com/424866).
-#else
+  if (base::android::BuildInfo::GetInstance()->sdk_int() < 21)
+    return;
+#endif
   TRACE_EVENT0("renderer", "RenderWidget::UpdateCompositionInfo");
   gfx::Range range = gfx::Range();
   if (should_update_range) {
@@ -1767,7 +1768,6 @@ void RenderWidget::UpdateCompositionInfo(bool should_update_range) {
   composition_range_ = range;
   Send(new InputHostMsg_ImeCompositionRangeChanged(
       routing_id(), composition_range_, composition_character_bounds_));
-#endif
 }
 
 void RenderWidget::convertViewportToWindow(blink::WebRect* rect) {