[Android WebView] OnMemoryPressure to drop tile memory

android_webview/browser/in_process_view_renderer.cc

Index: android_webview/browser/in_process_view_renderer.cc
diff --git a/android_webview/browser/in_process_view_renderer.cc b/android_webview/browser/in_process_view_renderer.cc
index 39bd2f6b889b0d7338ee44320991b894ca6dca9e..8ab28dfb45bb581289037215d62430b93040d047 100644
--- a/android_webview/browser/in_process_view_renderer.cc
+++ b/android_webview/browser/in_process_view_renderer.cc
@@ -316,6 +316,38 @@ 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.
+  client_->UpdateGlobalVisibleRect();
+  if (view_visible_ && window_visible_ &&
+      !cached_global_visible_rect_.IsEmpty()) {
+    return;
+  }
+
+  // Check that the expected EGL context is current. This may not be the case if
+  // the OnMemoryPressure callback is triggered manually in Chromium code.
+  DCHECK(last_egl_context_);
+  if (eglGetCurrentContext() != last_egl_context_)

[boliu, 2013/10/01 20:10:48]

This check is failing, so as is, this patch does nothing. Looking at why.

+    return;
+
+  TRACE_EVENT0("android_webview", "OnMemoryPressure");
+  ScopedAppGLStateRestore state_restore(ScopedAppGLStateRestore::MODE_ON_TRIM);
+  gpu::InProcessCommandBuffer::ProcessGpuWorkOnCurrentThread();
+  ScopedAllowGL allow_gl;
+
+  // Just set the memory limit to 0 and drop all tiles. This will be reset to
+  // normal levels in the next DrawGL call.
+  content::SynchronousCompositorMemoryPolicy policy;
+  policy.bytes_limit = 0;
+  policy.num_resources_limit = 0;
+  compositor_->SetMemoryPolicy(policy);
+}
+
 void InProcessViewRenderer::UpdateCachedGlobalVisibleRect() {
   client_->UpdateGlobalVisibleRect();
 }
@@ -342,8 +374,13 @@ bool InProcessViewRenderer::InitializeHwDraw() {
   hardware_failed_ = !compositor_->InitializeHwDraw(gl_surface_);
   hardware_initialized_ = true;
 
-  if (hardware_failed_)
+  if (hardware_failed_) {
     gl_surface_ = NULL;
+  } else {
+    memory_pressure_listener_.reset(new base::MemoryPressureListener(
+        base::Bind(&InProcessViewRenderer::OnMemoryPressure,
+                   base::Unretained(this))));
+  }
 
   return !hardware_failed_;
 }
@@ -643,6 +680,7 @@ void InProcessViewRenderer::OnDetachedFromWindow() {
     ScopedAllowGL allow_gl;
     compositor_->ReleaseHwDraw();
     hardware_initialized_ = false;
+    memory_pressure_listener_.reset();
   }
 
   gl_surface_ = NULL;