Make tab audible and muted states available for an extension API

* Added 'cause' parameter to mute method to indicate if muted state was changed by a user or by an extension.
* Added support for audible and muted event listeners.

A future patch that relies on these changes will update an API to make the audible and muted states available to extensions.

BUG=438903

Review URL: https://codereview.chromium.org/757033005

Cr-Commit-Position: refs/heads/master@{#319574}

AUTHORS

@@ -211,6 +211,7 @@ James Wei <james.wei@intel.com>
 James Willcox <jwillcox@litl.com>
 Janwar Dinata <j.dinata@gmail.com>
 Jared Shumway <jaredshumway94@gmail.com>
+Jared Sohn <jared.sohn@gmail.com>
 Jared Wein <weinjared@gmail.com>
 Jay Soffian <jaysoffian@gmail.com>
 Jeado Ko <haibane84@gmail.com>

chrome/browser/ui/cocoa/tabs/tab_strip_controller.mm

@@ -827,7 +827,8 @@ NSImage* Overlay(NSImage* ground, NSImage* overlay, CGFloat alpha) {
   if (!tabStripModel_->ContainsIndex(index))
     return;
   WebContents* contents = tabStripModel_->GetWebContentsAt(index);
-  chrome::SetTabAudioMuted(contents, !chrome::IsTabAudioMuted(contents));
+  chrome::SetTabAudioMuted(contents, !chrome::IsTabAudioMuted(contents),
+                           chrome::kMutedToggleCauseUser);
 }
 
 // Called when the user closes a tab. Asks the model to close the tab. |sender|

chrome/browser/ui/tabs/tab_strip_model.cc

@@ -1054,7 +1054,8 @@ void TabStripModel::ExecuteContextMenuCommand(
         content::RecordAction(UserMetricsAction("TabContextMenu_UnmuteTabs"));
       for (std::vector<int>::const_iterator i = indices.begin();
            i != indices.end(); ++i) {
-        chrome::SetTabAudioMuted(GetWebContentsAt(*i), mute);
+        chrome::SetTabAudioMuted(GetWebContentsAt(*i), mute,
+                                 chrome::kMutedToggleCauseUser);
       }
       break;
     }

chrome/browser/ui/tabs/tab_utils.cc

@@ -17,8 +17,22 @@
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/animation/multi_animation.h"
 
+struct LastMuteMetadata
+    : public content::WebContentsUserData<LastMuteMetadata> {
+  std::string cause;  // Extension ID or constant from header file
+                      // or empty string
+ private:
+  explicit LastMuteMetadata(content::WebContents* contents) {}
+  friend class content::WebContentsUserData<LastMuteMetadata>;
+};
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(LastMuteMetadata);
+
 namespace chrome {
 
+const char kMutedToggleCauseUser[] = "user";
+const char kMutedToggleCauseCapture[] = "auto-forced for capture";
+
 namespace {
 
 // Interval between frame updates of the tab indicator animations.  This is not
@@ -252,9 +266,25 @@ bool CanToggleAudioMute(content::WebContents* contents) {
   return false;
 }
 
-void SetTabAudioMuted(content::WebContents* contents, bool mute) {
+const std::string& GetTabAudioMutedCause(content::WebContents* contents) {
+  LastMuteMetadata::CreateForWebContents(contents);  // Create if not exists.
+  if (GetTabMediaStateForContents(contents) == TAB_MEDIA_STATE_CAPTURING) {
+    // For tab capture, libcontent forces muting off.
+    LastMuteMetadata::FromWebContents(contents)->cause =
+        kMutedToggleCauseCapture;
+  }
+  return LastMuteMetadata::FromWebContents(contents)->cause;
+}
+
+void SetTabAudioMuted(content::WebContents* contents,
+                      bool mute,
+                      const std::string& cause) {
   if (!contents || !chrome::CanToggleAudioMute(contents))
     return;
+
+  LastMuteMetadata::CreateForWebContents(contents);  // Create if not exists.
+  LastMuteMetadata::FromWebContents(contents)->cause = cause;
+
   contents->SetAudioMuted(mute);
 }
 

chrome/browser/ui/tabs/tab_utils.h

@@ -5,10 +5,12 @@
 #ifndef CHROME_BROWSER_UI_TABS_TAB_UTILS_H_
 #define CHROME_BROWSER_UI_TABS_TAB_UTILS_H_
 
+#include <string>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
+#include "content/public/browser/web_contents_user_data.h"
 
 class TabStripModel;
 
@@ -33,6 +35,11 @@ enum TabMediaState {
 
 namespace chrome {
 
+// String to indicate reason for muted state change (user, capture, extension
+// id, or empty string)
+extern const char kMutedToggleCauseUser[];
+extern const char kMutedToggleCauseCapture[];
+
 // Logic to determine which components (i.e., close button, favicon, and media
 // indicator) of a tab should be shown, given current state.  |capacity|
 // specifies how many components can be shown, given available tab width.
@@ -97,9 +104,17 @@ bool IsTabAudioMutingFeatureEnabled();
 // |contents|.
 bool CanToggleAudioMute(content::WebContents* contents);
 
-// Indicates/Sets whether all audio output from |contents| is muted.
+// Indicates whether all audio output from |contents| is muted.
 bool IsTabAudioMuted(content::WebContents* contents);
-void SetTabAudioMuted(content::WebContents* contents, bool mute);
+
+// Sets whether all audio output from |contents| is muted.
+// Cause is extensionid, kMutedToggleCause constant, or empty string
+void SetTabAudioMuted(content::WebContents* contents,
+                      bool mute,
+                      const std::string& cause);
+
+// Get cause of mute (extensionid, kMutedToggleCause constant, or empty string)
+const std::string& GetTabAudioMutedCause(content::WebContents* contents);
 
 // Returns true if the tabs at the |indices| in |tab_strip| are all muted.
 bool AreAllTabsMuted(const TabStripModel& tab_strip,

chrome/browser/ui/views/tabs/browser_tab_strip_controller.cc

@@ -299,7 +299,8 @@ void BrowserTabStripController::CloseTab(int model_index,
 
 void BrowserTabStripController::ToggleTabAudioMute(int model_index) {
   content::WebContents* const contents = model_->GetWebContentsAt(model_index);
-  chrome::SetTabAudioMuted(contents, !chrome::IsTabAudioMuted(contents));
+  chrome::SetTabAudioMuted(contents, !chrome::IsTabAudioMuted(contents),
+                           chrome::kMutedToggleCauseUser);
 }
 
 void BrowserTabStripController::ShowContextMenuForTab(