[Merge M51] aw: Avoid livelock bouncing between zero and non-zero memory

android_webview/browser/browser_view_renderer.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "android_webview/browser/browser_view_renderer.h"
 
 #include <utility>
 
 #include "android_webview/browser/browser_view_renderer_client.h"
 #include "android_webview/browser/child_frame.h"
@@ skipping 213 matching lines @@
   content::SynchronousCompositor::Frame frame =
       compositor_->DemandDrawHw(surface_size,
                                 gfx::Transform(),
                                 viewport,
                                 clip,
                                 viewport_rect_for_tile_priority,
                                 transform_for_tile_priority);
   if (!frame.frame.get()) {
     TRACE_EVENT_INSTANT0("android_webview", "NoNewFrame",
                          TRACE_EVENT_SCOPE_THREAD);
-    hardware_enabled_ = render_thread_manager_->HasFrameOnUI();
-    if (!hardware_enabled_)
-      UpdateMemoryPolicy();
-    return hardware_enabled_;
+    return render_thread_manager_->HasFrameOnUI();
   }
 
   std::unique_ptr<ChildFrame> child_frame = base::WrapUnique(new ChildFrame(
       frame.output_surface_id, std::move(frame.frame),
       GetCompositorID(compositor_), viewport_rect_for_tile_priority.IsEmpty(),
       transform_for_tile_priority, offscreen_pre_raster_,
       external_draw_constraints_.is_layer));
 
   ReturnUnusedResource(render_thread_manager_->PassUncommittedFrameOnUI());
   render_thread_manager_->SetFrameOnUI(std::move(child_frame));
@@ skipping 454 matching lines @@
   base::StringAppendF(&str,
                       "overscroll_rounding_error_: %s ",
                       overscroll_rounding_error_.ToString().c_str());
   base::StringAppendF(
       &str, "on_new_picture_enable: %d ", on_new_picture_enable_);
   base::StringAppendF(&str, "clear_view: %d ", clear_view_);
   return str;
 }
 
 }  // namespace android_webview