aw: Check compositor pointer before use

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 "android_webview/browser/browser_view_renderer_client.h"
 #include "android_webview/browser/shared_renderer_state.h"
 #include "android_webview/common/aw_switches.h"
 #include "base/auto_reset.h"
@@ skipping 111 matching lines @@
   if (level < TRIM_MEMORY_BACKGROUND && visible)
     return;
 
   // Just set the memory limit to 0 and drop all tiles. This will be reset to
   // normal levels in the next DrawGL call.
   SynchronousCompositorMemoryPolicy zero_policy;
   if (memory_policy_ == zero_policy)
     return;
 
   TRACE_EVENT0("android_webview", "BrowserViewRenderer::TrimMemory");
+  DCHECK(hardware_enabled_);
+  DCHECK(compositor_);
 
   RequestMemoryPolicy(zero_policy);
   EnforceMemoryPolicyImmediately(zero_policy);
 }
 
 SynchronousCompositorMemoryPolicy
 BrowserViewRenderer::CalculateDesiredMemoryPolicy() {
   SynchronousCompositorMemoryPolicy policy;
   size_t width = last_on_draw_global_visible_rect_.width();
   size_t height = last_on_draw_global_visible_rect_.height();
@@ skipping 10 matching lines @@
   // is also kTileAllocationStep.
   tiles = (tiles / kTileAllocationStep + 1) * kTileAllocationStep;
   policy.num_resources_limit = tiles;
   return policy;
 }
 
 // This function updates the cached memory policy in shared renderer state, as
 // well as the tile resource allocation in GlobalTileManager.
 void BrowserViewRenderer::RequestMemoryPolicy(
     SynchronousCompositorMemoryPolicy& new_policy) {
+  DCHECK(compositor_);
   GlobalTileManager* manager = GlobalTileManager::GetInstance();
 
   // The following line will call BrowserViewRenderer::SetMemoryPolicy().
   manager->RequestTiles(new_policy, tile_manager_key_);
 }
 
 void BrowserViewRenderer::SetMemoryPolicy(
     SynchronousCompositorMemoryPolicy new_policy,
     bool effective_immediately) {
   memory_policy_ = new_policy;
@@ skipping 116 matching lines @@
 }
 
 void BrowserViewRenderer::ReturnUnusedResource(
     scoped_ptr<cc::CompositorFrame> frame) {
   if (!frame.get())
     return;
 
   cc::CompositorFrameAck frame_ack;
   cc::TransferableResource::ReturnResources(
       frame->delegated_frame_data->resource_list, &frame_ack.resources);
-  if (!frame_ack.resources.empty())
+  if (compositor_ && !frame_ack.resources.empty())
     compositor_->ReturnResources(frame_ack);
 }
 
 void BrowserViewRenderer::ReturnResourceFromParent() {
   cc::CompositorFrameAck frame_ack;
   shared_renderer_state_->SwapReturnedResources(&frame_ack.resources);
-  if (!frame_ack.resources.empty()) {
+  if (compositor_ && !frame_ack.resources.empty()) {
     compositor_->ReturnResources(frame_ack);
   }
 }
 
 bool BrowserViewRenderer::OnDrawSoftware(jobject java_canvas) {
   if (!compositor_) {
     TRACE_EVENT_INSTANT0(
         "android_webview", "EarlyOut_NoCompositor", TRACE_EVENT_SCOPE_THREAD);
     return false;
   }
@@ skipping 110 matching lines @@
   attached_to_window_ = false;
   DCHECK(!hardware_enabled_);
 }
 
 void BrowserViewRenderer::ReleaseHardware() {
   DCHECK(hardware_enabled_);
   ReturnUnusedResource(shared_renderer_state_->PassCompositorFrame());
   ReturnResourceFromParent();
   DCHECK(shared_renderer_state_->ReturnedResourcesEmpty());
 
-  compositor_->ReleaseHwDraw();
+  if (compositor_) {
+    compositor_->ReleaseHwDraw();
+    SynchronousCompositorMemoryPolicy zero_policy;
+    RequestMemoryPolicy(zero_policy);
+  }
+
   hardware_enabled_ = false;
-
-  SynchronousCompositorMemoryPolicy zero_policy;
-  RequestMemoryPolicy(zero_policy);
   GlobalTileManager::GetInstance()->Remove(tile_manager_key_);
 }
 
 bool BrowserViewRenderer::IsVisible() const {
   // Ignore |window_visible_| if |attached_to_window_| is false.
   return view_visible_ && (!attached_to_window_ || window_visible_);
 }
 
 gfx::Rect BrowserViewRenderer::GetScreenRect() const {
   return gfx::Rect(client_->GetLocationOnScreen(), gfx::Size(width_, height_));
 }
 
 void BrowserViewRenderer::DidInitializeCompositor(
     content::SynchronousCompositor* compositor) {
   TRACE_EVENT0("android_webview",
                "BrowserViewRenderer::DidInitializeCompositor");
   DCHECK(compositor);
   DCHECK(!compositor_);
   compositor_ = compositor;
 }
 
 void BrowserViewRenderer::DidDestroyCompositor(
     content::SynchronousCompositor* compositor) {
   TRACE_EVENT0("android_webview", "BrowserViewRenderer::DidDestroyCompositor");
   DCHECK(compositor_);
+  SynchronousCompositorMemoryPolicy zero_policy;
+  if (hardware_enabled_) {
+    RequestMemoryPolicy(zero_policy);
+  }
+  DCHECK(memory_policy_ == zero_policy);
   compositor_ = NULL;
-  SynchronousCompositorMemoryPolicy zero_policy;
-  DCHECK(memory_policy_ == zero_policy);
 }
 
 void BrowserViewRenderer::SetContinuousInvalidate(bool invalidate) {
   if (compositor_needs_continuous_invalidate_ == invalidate)
     return;
 
   TRACE_EVENT_INSTANT1("android_webview",
                        "BrowserViewRenderer::SetContinuousInvalidate",
                        TRACE_EVENT_SCOPE_THREAD,
                        "invalidate",
@@ skipping 303 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