Don't share renderers between unrelated tabs on Android.

content/browser/renderer_host/render_process_host_impl.cc

 // Copyright (c) 2012 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.
 
 // Represents the browser side of the browser <--> renderer communication
 // channel. There will be one RenderProcessHost per renderer process.
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 
 #include <algorithm>
@@ skipping 376 matching lines @@
 
 // Stores the maximum number of renderer processes the content module can
 // create.
 static size_t g_max_renderer_count_override = 0;
 
 // static
 size_t RenderProcessHost::GetMaxRendererProcessCount() {
   if (g_max_renderer_count_override)
     return g_max_renderer_count_override;
 
-  // Defines the maximum number of renderer processes according to the
-  // amount of installed memory as reported by the OS. The calculation
-  // assumes that you want the renderers to use half of the installed
-  // RAM and assuming that each WebContents uses ~40MB.
-  // If you modify this assumption, you need to adjust the
-  // ThirtyFourTabs test to match the expected number of processes.
+  // On Android we don't maintain a limit of renderer process hosts - we are

[jam, 2014/07/16 20:22:07]

nit: put the comment inside the ifdef to make it clear that this is for android

[ppi, 2014/07/17 10:14:45]

Done.

+  // happy with keeping a lot of these, as long as the number of live renderer
+  // processes remains reasonable, and on Android the OS takes care of that.
+#if defined(OS_ANDROID)
+  return std::numeric_limits<size_t>::max();
+#endif
+
+  // On other platforms, we calculate the maximum number of renderer process
+  // hosts according to the amount of installed memory as reported by the OS.
+  // The calculation assumes that you want the renderers to use half of the
+  // installed RAM and assuming that each WebContents uses ~40MB.  If you modify
+  // this assumption, you need to adjust the ThirtyFourTabs test to match the
+  // expected number of processes.
   //
-  // With the given amounts of installed memory below on a 32-bit CPU,
-  // the maximum renderer count will roughly be as follows:
+  // With the given amounts of installed memory below on a 32-bit CPU, the
+  // maximum renderer count will roughly be as follows:
   //
   //   128 MB -> 3
   //   512 MB -> 6
   //  1024 MB -> 12
   //  4096 MB -> 51
   // 16384 MB -> 82 (kMaxRendererProcessCount)
 
   static size_t max_count = 0;
   if (!max_count) {
     const size_t kEstimatedWebContentsMemoryUsage =
@@ skipping 1946 matching lines @@
 void RenderProcessHostImpl::GpuMemoryBufferAllocated(
     IPC::Message* reply,
     const gfx::GpuMemoryBufferHandle& handle) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   ChildProcessHostMsg_SyncAllocateGpuMemoryBuffer::WriteReplyParams(reply,
                                                                     handle);
   Send(reply);
 }
 
 }  // namespace content