[Android WebView] OnMemoryPressure to drop tile memory

android_webview/browser/in_process_view_renderer.cc

 // Copyright 2013 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/in_process_view_renderer.h"
 
 #include <android/bitmap.h>
 
 #include "android_webview/browser/aw_gl_surface.h"
 #include "android_webview/browser/scoped_app_gl_state_restore.h"
@@ skipping 298 matching lines @@
   std::stringstream size;
   size << default_tile_size;
   cl->AppendSwitchASCII(switches::kDefaultTileWidth, size.str());
   cl->AppendSwitchASCII(switches::kDefaultTileHeight, size.str());
 }
 
 bool InProcessViewRenderer::RequestProcessGL() {
   return client_->RequestDrawGL(NULL);
 }
 
+void InProcessViewRenderer::OnMemoryPressure(
+    base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level) {
+  // Nothing to release.
+  if (!attached_to_window_ || !compositor_ || !hardware_initialized_)
+    return;
+
+  // Do not release resources on view we expect to get DrawGL soon.
+  if (view_visible_ && window_visible_)
+    return;
+
+  TRACE_EVENT_INSTANT0(
+      "android_webview", "OnMemoryPressure", TRACE_EVENT_SCOPE_THREAD);
+  ScopedAppGLStateRestore state_restore(ScopedAppGLStateRestore::MODE_ON_TRIM);
+  gpu::InProcessCommandBuffer::ProcessGpuWorkOnCurrentThread();
+  ScopedAllowGL allow_gl;

[joth, 2013/10/01 11:10:46]

GL not valid if this is a 'fake' memory pressure?

Should we use the new "process with GL valid" Runnable thing ?

+
+  content::SynchronousCompositorMemoryPolicy policy;
+  policy.bytes_limit = 0;
+  policy.num_resources_limit = 0;
+  compositor_->SetMemoryPolicy(policy);

[joth, 2013/10/01 11:10:46]

comment this will get set back upward on the next draw?

+}
+
 void InProcessViewRenderer::UpdateCachedGlobalVisibleRect() {
   client_->UpdateGlobalVisibleRect();
 }
 
 bool InProcessViewRenderer::OnDraw(jobject java_canvas,
                                    bool is_hardware_canvas,
                                    const gfx::Vector2d& scroll,
                                    const gfx::Rect& clip) {
   scroll_at_start_of_frame_  = scroll;
   if (is_hardware_canvas && attached_to_window_ && HardwareEnabled()) {
@@ skipping 597 matching lines @@
     base::StringAppendF(&str,
                         "surface width height: [%d %d] ",
                         draw_info->width,
                         draw_info->height);
     base::StringAppendF(&str, "is_layer: %d ", draw_info->is_layer);
   }
   return str;
 }
 
 }  // namespace android_webview