[Android WebView] OnMemoryPressure to drop tile memory

android_webview/browser/browser_view_renderer.h

 // Copyright (c) 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.
 
 #ifndef ANDROID_WEBVIEW_BROWSER_BROWSER_VIEW_RENDERER_H_
 #define ANDROID_WEBVIEW_BROWSER_BROWSER_VIEW_RENDERER_H_
 
 #include "base/android/scoped_java_ref.h"
+#include "base/memory/memory_pressure_listener.h"
 #include "skia/ext/refptr.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/vector2d_f.h"
 
 class SkPicture;
 struct AwDrawGLInfo;
 struct AwDrawSWFunctionTable;
 
 namespace content {
@@ skipping 91 matching lines @@
                       const gfx::Vector2d& scroll,
                       const gfx::Rect& clip) = 0;
 
   // Called in response to a prior Client::RequestDrawGL() call. See
   // AwDrawGLInfo documentation for more details of the contract.
   virtual void DrawGL(AwDrawGLInfo* draw_info) = 0;
 
   // The global visible rect changed and this is the new value.
   virtual void SetGlobalVisibleRect(const gfx::Rect& visible_rect) = 0;
 
+  virtual void OnMemoryPressure(
+      base::MemoryPressureListener::MemoryPressureLevel
+          memory_pressure_level) = 0;
+
   // CapturePicture API methods.
   virtual skia::RefPtr<SkPicture> CapturePicture(int width, int height) = 0;
   virtual void EnableOnNewPicture(bool enabled) = 0;
 
   // View update notifications.
   virtual void SetIsPaused(bool paused) = 0;
   virtual void SetViewVisibility(bool visible) = 0;
   virtual void SetWindowVisibility(bool visible) = 0;
   virtual void OnSizeChanged(int width, int height) = 0;
   virtual void OnAttachedToWindow(int width, int height) = 0;
   virtual void OnDetachedFromWindow() = 0;
 
   // Sets the scale for logical<->physical pixel conversions.
   virtual void SetDipScale(float dip_scale) = 0;
 
   // Set the root layer scroll offset to |new_value|.
   virtual void ScrollTo(gfx::Vector2d new_value) = 0;
 
   // Android views hierarchy gluing.
   virtual bool IsAttachedToWindow() = 0;
   virtual bool IsVisible() = 0;
   virtual gfx::Rect GetScreenRect() = 0;
 
   virtual ~BrowserViewRenderer() {}
 };
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_BROWSER_VIEW_RENDERER_H_